In thermal printing, it is generally well known to render images by heating and pressing one or more donor materials such as dye, colorant or other coating against a receiver medium. The donor materials are provided in sized donor patches on a moveable web known as a donor ribbon. The donor patches are organized on the ribbon into donor patch sets, each donor patch set contains all of the donor patches that are to be used to record an image on the receiver medium. For full color images, multiple colored dye sets can be used, such as yellow, magenta and cyan donor dye patches. Arrangements of other color patches can be used in like fashion within a donor patch set. Additionally, each donor set can include an overcoat or sealant layer.
It will be appreciated from this that it is necessary to neutrally calibrate the printer by methods known to those skilled in the art. This calibration is performed to ensure that the output performance of the thermal printer remains within tolerance from unit-to-unit and media set to media set. Such calibration can be done at the factory by means of multiple look-up-tables (LUTs), one for each color. Additionally, the thermal printhead voltage may be adjusted for the total range of printer operation. As this calibration is performed at the factory, there is no means to compensate for onsite variability involving printer usage, media changes and environmental conditions at the customer site. In some of these situations, better color adjustment is required to adjust the printer settings to compensate for these variables.